Then I think that what I would like to do with my life before leaving, is to leave a legacy of love, constancy, respect and values to my son.

This is so beautiful. We all think of leaving money for our children, but I love your thoughts and feelings for your child. You must have gone through a lot in life and that shows in your words, the pain that you feel towards life. But remember one thing, we are all going through different types of tests in our life and we have chosen to go through it by ourselves at a higher level to progress in our soul journey. It's easy to say, but yet, next time when you have a difficult condition, feel and know that this test is going to progress your soul at higher levels.
Another thing is that nothing is permanent in life, so if good days are not forever, so are the bad days. So always move ahead with a positive mindset and feelings for life.
Good luck with your old-age home dream, I wish it comes true